Oil supply apparatus for hermetic compressor

ABSTRACT

Disclosed is an oil supply apparatus for a hermetic compressor including an oil feeder mounted at a bottom end of a crank shaft rotated by a driving unit, for sucking oil, an oil passage formed inside the crank shaft, for guiding the oil sucked by the oil feeder, and an oil injection hole formed on a sleeve inserted onto an eccentric unit formed at the top end of the crank shaft, for injecting the oil sucked into the oil passage into a cylinder for compressing fluid. The oil supply apparatus for the hermetic compressor improves efficiency of the compressor by efficiently cooling the cylinder by sufficiently supplying the oil stored at the lower portion of the casing to the cylinder.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an oil supply apparatus for a hermetic compressor, and more particularly to, an oil supply apparatus for a hermetic compressor which can improve efficiency of the compressor by cooling a cylinder by mainly supplying oil to the cylinder.

2. Description of the Background Art In general, various types of compressors can be employed according to compression methods. A hermetic reciprocal type compressor has been mostly used for an air conditioning apparatus requiring a small size and a light weight.

FIG. 1 is a cross-sectional view illustrating a conventional hermetic compressor.

The conventional hermetic compressor includes a casing 104 having a hermetic space, being connected to a suction tube 102 and a discharge tube (not shown), and storing oil 106 at its lower portion, a driving unit 108 disposed at the lower portion of the casing 104, for generating a rotary force, a compression unit 110 disposed at the upper portion of the casing 104, for compressing fluid sucked into the suction tube 102 by the rotary force generated by the driving unit 108, and discharging the compressed fluid to the discharge tube (not shown), and an oil supply apparatus for performing a lubrication operation by supplying the oil 106 stored at the lower portion of the casing 104 to rubbed parts.

The driving unit 108 includes a stator 112 fixedly disposed on the inner circumference of the casing 104, for receiving power from an external source, a rotor 114 disposed on the inner circumference of the stator 112, and rotated by interactions with the stator 112 when power is applied to the stator 112, and a crank shaft 118 fixed to and rotated with the rotor 114, and rotatably supported by a frame 116 fixed to the casing 104.

The compression unit 110 includes a connecting rod 122 connected to an eccentric unit 120 eccentrically formed at the top end of the crank shaft 118, and linearly reciprocated when the crank shaft 118 is rotated, a cylinder 126 being fixedly disposed on the top surface of the frame 116, and having a compression chamber 124 for compressing the fluid, a piston 128 connected to and linearly moved with the connecting rod 122, and disposed to slide into the cylinder 126, for compressing the fluid sucked into the compression chamber 124 of the cylinder 126, and a valve assembly 130 mounted at one side of the cylinder 126, for supplying the fluid to the cylinder 126, and discharging refrigerants compressed by the piston 128.

A sleeve 132 is slidably inserted onto the outer circumference of the eccentric unit 120, and the connecting rod 122 is mounted on the outer circumference of the sleeve 132.

As illustrated in FIG. 2, the sleeve 132 is formed in a cylindrical shape having its upper and lower portions opened, so that the sleeve 132 can be slidably inserted onto the outer circumference of the eccentric unit 120.

The valve assembly 130 includes a suction valve (not shown) mounted at one opened side of the cylinder 126, for opening or closing sucked fluid, and a discharge valve (not shown) mounted at the other opened side of the cylinder 126, for opening or closing discharged fluid. A head cover 136 having a suction space for sucking fluid and a discharge space for discharging fluid is mounted on the outside surface of the valve assembly 130.

The oil supply apparatus includes an oil feeder 140 mounted at the bottom end of the crank shaft 116, for sucking the oil 106 when the crank shaft 116 is rotated, and an oil passage 142 formed in the length direction of the crank shaft 116, for supplying the oil 106 sucked by the oil feeder 140 to each rubbed part.

FIG. 3 is a cross-sectional view illustrating the compression unit of the conventional hermetic compressor.

In the conventional hermetic compressor, when power is applied to the driving unit 108, the crank shaft 118 is rotated by interactions between the stator 112 and the rotor 114, and the connecting rod 112 connected to the eccentric unit 120 of the crank shaft 118 is linearly reciprocated. The piston 128 connected to the connecting rod 122 is linearly reciprocated inside the cylinder 126, for compressing the fluid.

Here, the oil feeder 140 mounted at the bottom end of the crack shaft 118 is operated by the rotation of the crank shaft 118, for sucking the oil 106 stored at the lower portion of the casing 104 into the oil passage 142. The oil 106 sucked into the oil passage 142 is injected in the upward direction of the eccentric unit 120 as indicated by arrows P through the top surface of the eccentric unit 120, thereby lubricating the rubbed parts.

In the conventional hermetic compressor, the oil supply apparatus injects the oil 106 in the upward direction of the eccentric unit 120, and thus does not efficiently supply the oil 106 to the cylinder 126 disposed in the horizontal direction to the eccentric unit 120. Accordingly, the cylinder 126 is not sufficiently cooled, and thus efficiency of the compressor is deteriorated.

As shown in the graph of FIG. 4, when the refrigerants are compressed in the compression chamber 124 inside the cylinder 126, compression efficiency is the highest in the isothermal compression. That is, compression efficiency can be improved by sufficiently cooling the cylinder 126. However, the conventional oil supply apparatus does not sufficiently supply the oil 106 to the cylinder 126, and thus not efficiently cool the cylinder 126, thereby deteriorating efficiency of the compressor.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide an oil supply apparatus for a hermetic compressor which can improve efficiency of the compressor by efficiently cooling a cylinder by sufficiently supplying oil stored at a is lower portion of a casing to the cylinder.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided an oil supply apparatus for a hermetic compressor, including: an oil feeder mounted at a bottom end of a crank shaft rotated by a driving unit, for sucking oil; an oil passage formed inside the crank shaft, for guiding the oil sucked by the oil feeder; and an oil injection hole formed on a sleeve inserted onto an eccentric unit formed at the top end of the crank shaft, for injecting the oil sucked into the oil passage into a cylinder for compressing fluid.

The sleeve is slidably inserted onto the eccentric unit, and has its top surface sealed up, the oil injection hole being formed at the portion of the sleeve facing the cylinder.

The oil injection hole is inclined in the rotary direction of the crank shaft.

The oil injection hole is inclined at 900 from an imaginary line formed from the center of the sleeve in the radial direction.

According to another aspect of the present invention, an oil supply apparatus for a hermetic compressor includes: an oil feeder mounted at a bottom end of a crank shaft rotated by a driving unit, for sucking oil; an oil passage formed inside the crank shaft, for guiding the oil sucked by the oil feeder; an upper oil injection hole formed at an upper portion of a sleeve inserted onto an eccentric unit formed at the top end of the crank shaft, for injecting the oil sucked into the oil passage into a head cover through which fluid passes; and a lower oil injection hole formed at the lower portion of the sleeve, for injecting the oil sucked into the oil passage into a cylinder for compressing the fluid.

The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

In the drawings:

FIG. 1 is a cross-sectional view illustrating a conventional hermetic compressor;

FIG. 2 is a perspective view illustrating a sleeve of the conventional hermetic compressor;

FIG. 3 is a cross-sectional view illustrating a compression unit of the conventional hermetic compressor;

FIG. 4 is a graph showing P-V lines of the conventional compressor;

FIG. 5 is a cross-sectional view illustrating a hermetic compressor in accordance with a first embodiment of the present invention;

FIG. 6 is a perspective view illustrating a sleeve of the hermetic compressor in accordance with the first embodiment of the present invention;

FIG. 7 is a cross-sectional view taken along line VII-VII of FIG. 6;

FIG. 8 is a cross-sectional view illustrating a compression unit of the hermetic compressor in accordance with the first embodiment of the present invention;

FIGS. 9A to 9D are operational state views illustrating operational states of the hermetic compressor in accordance with the first embodiment of the present invention;

FIG. 10 is a perspective view illustrating a sleeve of a hermetic compressor in accordance with a second embodiment of the present invention;

FIG. 11 is a cross-sectional view taken along line XI-XI of FIG. 10;

FIG. 12 is a cross-sectional view illustrating a compression unit of the hermetic compressor in accordance with the second embodiment of the present invention;

FIG. 13 is a graph showing P-V lines of the hermetic compressor in accordance with the present invention; and

FIG. 14 is a graph showing T-S lines of the hermetic compressor in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

An oil supply apparatus for a hermetic compressor in accordance with the 1o most preferable embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 5 is a cross-sectional view illustrating a hermetic compressor in accordance with a first embodiment of the present invention.

The hermetic compressor includes a casing 10 having a hermetic space, is being connected to a suction tube 12 and a discharge tube (not shown), and storing oil 18 at its lower portion, a driving unit 14 disposed at the lower portion of the casing 10, for generating a rotary force, a compression unit 16 disposed at the upper portion of the casing 10, for compressing fluid sucked into the suction tube 12 by the rotary force generated by the driving unit 14, and discharging the compressed fluid to the discharge tube (not shown), and an oil supply apparatus for supplying the oil 18 to rubbed parts of the compression unit 16, and also supplying the oil 18 to a cylinder 20 of the compression unit 16.

The driving unit 14 includes a stator 24 damply supported by damping springs 22 mounted at the lower portion of the casing 10, for receiving power from an external source, a rotor 26 disposed on the inner circumference of the stator 24, and rotated by interactions with the stator 24 when power is applied to the stator 24, and a crank shaft 28 fixed to and rotated with the rotor 26, and rotatably supported by a frame 30 fixed to the casing 10.

The compression unit 16 includes a connecting rod 32 connected to the top end of the crank shaft 28, and linearly reciprocated when the crank shaft 28 is rotated, a cylinder 20 being fixedly disposed on the top surface of the frame 30, and having a compression chamber 34 for compressing fluid, a piston 36 connected to and linearly moved with the connecting rod 32, and disposed to slide into the cylinder 20, for compressing the fluid sucked into the cylinder 20, and a valve assembly 38 mounted at one side of the cylinder 20, for supplying the fluid to the cylinder 20, and discharging refrigerants compressed by the piston 36.

An eccentric unit 40 having its axial center eccentric from the center of the crank shaft 28 is formed at the top end of the crank shaft 28, a sleeve 42 is slidably disposed on the outer circumference of the eccentric unit 40, and one side end of the connecting rod 32 is fixed to the outer circumference of the sleeve 42.

The valve assembly 38 includes a suction valve 44 mounted at one opened side of the cylinder 20, for opening or closing sucked fluid, a discharge valve 46 mounted at the other opened side of the cylinder 20, for opening or closing discharged fluid, and a head cover 48 being fixed to the cylinder 20, and having a suction space for sucking fluid and a discharge sDace for discharging fluid.

The oil supply apparatus includes an oil feeder 50 mounted at the bottom end of the crank shaft 28, for sucking the oil 18 when the crank shaft 28 is rotated, an oil passage 52 formed in the length direction of the crank shaft 28, for transferring the oil 18 sucked by the oil feeder 50, and an oil injection hole 54 formed on the sleeve 42, for injecting the oil 18 guided by the oil passage 52 into the cylinder 20.

As depicted in FIGS. 6 and 7, the sleeve 42 is formed in a cylindrical shape having its top surface sealed up, and slidably disposed on the outer circumference of the eccentric unit 40. The oil injection hole 54 for injecting the oil 18 is formed at the portion of the sleeve 42 facing the cylinder 20.

A chamber 56 is formed between the sleeve 42 and the eccentric unit 40. The oil 18 supplied through the oil passage 52 is filled in the chamber 56. The oil 18 filled in the chamber 56 is injected into the cylinder 20 through the oil injection hole 54.

The oil injection hole 54 is inclined at a predetermined angle in the rotary direction of the crank shaft 28 in order to inject more oil 18 into the cylinder 20. Preferably, the oil injection hole 54 is inclined at an angle θ from an imaginary line Q formed from the center of the sleeve 42 in the radial direction.

In consideration of a potential energy by a centrifugal force and a kinetic energy by rotation, most advantageously, the inclination angle θ of the oil injection hole is 90° from the imaginary line Q.

The operation of the hermetic compressor in accordance with the first embodiment of the present invention will now be described.

FIG. 8 is a cross-sectional view illustrating the compression unit of the hermetic compressor in accordance with the first embodiment of the present invention.

When power is applied to the driving unit 14, the crank shaft 28 is rotated by interactions between the stator 24 and the rotor 26, and the connecting rod 32 connected to the eccentric unit 40 formed at the top end of the crank shaft 28 is linearly reciprocated. The piston 36 connected to the connecting rod 32 is linearly reciprocated inside the cylinder 20, for compressing the fluid sucked into the compression chamber 34 of the cylinder 20. Here, when the piston 36 moves backward, the suction valve 44 is opened and the fluid is sucked into the compression chamber 34, and when the piston 36 moves forward, the discharge valve 46 is opened and the compressed fluid is externally discharged through the discharge tube (not shown).

The oil feeder 50 mounted at the bottom end of the crack shaft 28 is operated by the rotation of the crank shaft 28, for sucking the oil 18. The oil 18 sucked by the oil feeder 50 is guided in the upward direction of the crank shaft 28 through the oil passage 52. The oil 18 guided by the oil passage 52 is sucked into the chamber 56 formed at the sleeve 42. The oil 18 sucked into the chamber 56 is injected into the cylinder 20 through the oil injection hole 54 formed on the sleeve 42, thereby cooling the cylinder 20 and lubricating the rubbed parts.

Since the oil injection hole 54 is inclined at the angle θ in the rotary direction of the crank shaft 28 from the imaginary line Q extended from the center of the sleeve 42 in the radial direction, more oil 18 can be injected into the cylinder 20 through the oil injection hole 54, thereby efficiently cooling the cylinder 20.

FIGS. 9A to 9D are operational state views illustrating oil injection positions by rotation of the crank shaft of the hermetic compressor in accordance with the first embodiment of the present invention.

Since the sleeve 42 is slidably inserted onto the eccentric unit 40 and the connecting rod 32 is mounted on the outer circumference of the sleeve 42, the oil injection hole 54 of the sleeve 42 always faces the cylinder 20.

When the eccentric unit 40 is rotated by rotation of the crank shaft 28 to reach the positions of FIGS. 9A and 9B, the oil 18 sucked into the chamber 56 of the sleeve 42 is injected into the cylinder 20 through the oil injection hole 54 by the centrifugal force as indicated by arrows R, for cooling the cylinder 20. When the eccentric unit 40 is more rotated to reach the positions of FIGS. 9C and 9D, the centrifugal force is not generated, and thus the oil 18 is not injected through the oil injection hole 54 but supplied to the rubbed parts of the inner circumference of the sleeve 42, for lubricating the rubbed parts.

FIG. 10 is a perspective view illustrating a sleeve of a hermetic compressor in accordance with a second embodiment of the present invention, FIG. 11 is a cross-sectional view taken along line XI-XI of FIG. 10, and FIG. 12 is a cross-sectional view illustrating a compression unit of the hermetic compressor in accordance with the second embodiment of the present invention.

The hermetic compressor of the second embodiment is substantially identical to the hermetic compressor of the first embodiment except for the sleeve.

A sleeve 70 is formed in a cylindrical shape having its top surface sealed up, and slidably disposed on the outer circumference of the eccentric unit 40. An upper oil injection hole 72 and a lower oil injection hole 74 for injecting oil are formed at the portion of the sleeve 70 facing the cylinder 20, respectively.

The lower oil injection hole 74 is formed at the lower portion of the sleeve 70, for injecting oil into the cylinder 20 to cool the cylinder 20, and the upper oil injection hole 72 is formed at the upper portion of the sleeve 70, for injecting oil farther than the lower oil injection hole 74, namely, injecting oil into the head cover 48 positioned farther than the cylinder 20 to cool the head cover 48.

Referring to FIG. 11, the upper oil injection hole 72 and the lower oil injection hole 74 are inclined at a predetermined angle in the rotary direction of the crank shaft 28, for injecting more oil into the cylinder 20 and the head cover 48. Preferably, the upper oil injection hole 72 and the lower oil injection hole 74 are inclined at an angle θ from an imaginary line Q formed from the center of the sleeve 42 in the radial direction. Preferably, the angle θ is 90°.

In the oil supply apparatus for the hermetic compressor of the second embodiment, the oil injected through the upper oil injection hole 72 formed on the sleeve 70 is supplied to the head cover 48 as indicated by arrows E, for cooling the head cover 48, and the oil injected through the lower oil injection hole 74 formed on the sleeve 70 is supplied to the cylinder 20 as indicated by arrows F, for cooling the cylinder 20.

FIG. 13 is a graph showing P-V lines of the hermetic compressor in accordance with the present invention. The oil supply apparatus for the hermetic compressor cools the cylinder, and thus reduces the temperature of the refrigerants compressed in the cylinder, thereby performing the isothermal process. As shown in FIG. 13, the line M of the present invention is lower than the general line L in the compression process of 1 to 2. Therefore, the input for the operation of the compressor can be reduced by the section N, which results in high efficiency of the compressor.

FIG. 14 is a graph showing T-S lines of the hermetic compressor in accordance with the present invention. The conventional compressor shows arrows V in the compression process. However, when the oil supply apparatus of the present invention cools the refrigerants by cooling the cylinder, the isothermal process is performed in the compression process as indicated by arrows W. As a result, efficiency of the compressor is improved.

As discussed earlier, in accordance with the present invention, the oil supply apparatus for the hermetic compressor cools the cylinder by forming the oil injection hole facing the cylinder on the sleeve and injecting the oil into the cylinder. Accordingly, the isothermal compression is performed to improve efficiency of the compressor.

In addition, the oil supply apparatus for the hermetic compressor forms the upper and lower oil injection holes on the sleeve, and injects the oil into the head cover through the upper oil injection hole and into the cylinder through the lower oil injection hole. Therefore, the oil supply apparatus for the hermetic compressor cools the refrigerants inside the cylinder and the head cover, thereby improving efficiency of the compressor.

As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims. 

1. An oil supply apparatus for a hermetic compressor, comprising: an oil feeder mounted at a bottom end of a crank shaft rotated by a driving unit, for sucking oil; an oil passage formed inside the crank shaft, for guiding the oil sucked by the oil feeder; and an oil injection hole formed on a sleeve inserted onto an eccentric unit formed at the top end of the crank shaft, for injecting the oil sucked into the oil passage into a cylinder for compressing fluid.
 2. The apparatus of claim 1, wherein the sleeve is slidably inserted onto the eccentric unit, and has its top surface sealed up, the oil injection hole being formed at the portion of the sleeve facing the cylinder.
 3. The apparatus of claim 2, wherein a chamber filled with the oil sucked into the oil passage is formed in the sleeve.
 4. The apparatus of claim 2, wherein the oil injection hole is inclined in the rotary direction of the crank shaft.
 5. The apparatus of claim 4, wherein the oil injection hole is inclined at 90° from an imaginary line formed from the center of the sleeve in the radial direction.
 6. An oil supply apparatus for a hermetic compressor, comprising: an oil feeder mounted at a bottom end of a crank shaft rotated by a driving unit, for sucking oil; an oil passage formed inside the crank shaft, for guiding the oil sucked by the oil feeder; an upper oil injection hole formed at an upper portion of a sleeve inserted onto an eccentric unit formed at the top end of the crank shaft, for injecting the oil sucked into the oil passage into a head cover through which fluid passes; and a lower oil injection hole formed at the lower portion of the sleeve, for injecting the oil sucked into the oil passage into a cylinder for compressing the fluid.
 7. The apparatus of claim 6, wherein the upper oil injection hole and the lower oil injection hole are inclined in the rotary direction of the crank shaft.
 8. The apparatus of claim 6, wherein the upper oil injection hole and the lower oil injection hole are inclined at 90° from an imaginary line formed from the center of the sleeve in the radial direction. 